Currently, insulating ropes available at the market are mainly prepared by weaving and stranding silk or synthetic fiber. In the field of live working, given requirements for the insulation property and deformation of ropes, silk ropes and synthetic fiber ropes are mainly adopted. The damp-proof treatment of silk ropes and synthetic fiber ropes generally adopts physical attachment via damp-proof agents instead of chemical bond connection, so after being washed for certain times, the damp-proof performance of the ropes is reduced significantly, leading to a short service life. Furthermore, with erection of UHV transmission lines, the size and weight of various fittings on the transmission lines increase, while the fittings need to be lifted in the live working process; however, the strength of the existing silk ropes and synthetic fiber ropes cannot meet requirements of live working to some extent, and as a result, some working projects fail to proceed successfully.
Therefore, it is necessary to develop new insulation ropes for live working. Compared with the silk ropes and existing synthetic fiber ropes, the new insulation ropes should have better and more stable damp-proof performance, higher strength and better ultraviolet aging resistance. The novel high-strength, damp-proof and ultraviolet aging resistant insulation ropes can transfer large-tonnage stress of the live working items on a tower onto the ground, thereby reducing the labor intensity of operators on the tower and ensuring working safety. The successful development of the insulation ropes will bring the third revolution of UHV live working.
PBO fiber is a polyparaphenylene benzobisoxazole fiber whose fibrils are composed of PBO molecular chains orienting in the direction of the fiber axis with diameter between 10 and 50 nm and there are many capillary pores between the fibrils, which are connected to each other by means of cracks between the fibrils or openings of the fibrils.
PBO fiber has a perfect comprehensive performance, known as ultra-high performance fibers of the new era. Its tensile strength, monofilament strength of up to 5 Gpa, the tensile modulus of up to 300 Gpa, is twice that of the para-aramid fiber and 10 times that of the steel wire of the same diameter, and its density is only ⅕ of steel wire. The wear resistance on metal is better than that of aramid fiber, and the deformation coefficient is small, its thermal expansion coefficient is only −6 ppm/° C. The thermal degradation temperature in the air is about 650° C., and 700° C. in the nitrogen or argon gas environment, which is 100° C. higher than the aramid fiber; the limit of oxygen index of the PBO fiber is 68, highest among the polymers; it is smoldering even in open flame, so that it has self-flame retardancy. In addition, it has high impact resistance, and the energy needed to penetrate through its fabric is 2 times as much as that for penetrating Kevlar fiber. Therefore, PBO fiber is not only widely used in fields of national defense, aerospace and other advanced fields, but also can be widely applied to replace the conventional industrial production process and the upgrades of products with high temperature resistance, flame retardant, high performance, such as fiber reinforced material, high tensile strength such as rope or cable material, bridge cable, cable, sailing sailboat the operating lever and rowing with canvas, bullet-proof vests, nautical clothing, anti-high temperature & cut resistant gloves, high temperature and high pressure resistant gloves, PBO fiber composite materials are applied to aircrafts, space crafts, rocket outer structures and internal force bearing structures.
Given its excellent mechanical property and heat stability, BPO fiber becomes the first choice for insulation ropes for live working. Although PBO fiber has many advantages, there are still some serious drawbacks, such as PBO fiber is highly hydroscopic, and prone to deep fibrillation after damp, resulting in slip of PBO fibrils, and a sharp decline in mechanical properties; in addition, PBO fiber in the ultraviolet light irradiation can be prone to rapid aging phenomenon. The existence of these defects makes the PBO fiber rope's life shorter and cost higher, and severely limits its scope of application.
The surface treatment measures commonly used in the prior art is to deal with the PBO fiber with the help of a waterproofing agent and an ultraviolet absorber, or a shield agent. However, due to the absence of weak chemical bonds in the PBO molecular structure and a lack of the active groups, its surface is smooth and the free energy is low, making it difficult to connect with other functional groups, such as waterproofing group, anti-ultraviolet radiation group, etc. Therefore, these prior art methods have no obvious effects, and it is difficult to effectively solve the technical problems such as easy moisture absorption, decrease of strength and rapid aging in outdoor application.